Hazard Overview

A power take-off (PTO) shaft transfers mechanical power from a tractor to an implement. While some PTO-driven equipment is operated from the tractor seat, other types of farm equipment, such as elevators, grain augers, silage blowers, and so on, are operated in a stationary position, letting the operator leave the tractor and move around in the vicinity of the implement.

A PTO shaft rotates at a speed of either 540 rpm (9 rotations per second) or 1,000 rpm (16.6 rotations per second). At these high rates of speed, a person's limb can be pulled into and wrapped around a PTO stub or driveline shaft several times before the person can react. The fast rotation speed, operator error, and lack of proper guarding make PTOs a persistent hazard on farms and ranches. Injuries that can be sustained from PTO incidents include severe contusion, cuts, spinal and neck injuries, dislocations, broken bones, amputations and scalping. Some incidents can result in fatalities.

Basic safety recommendations include the following:

Never step over a rotating shaft.

Make sure that your tractor and machinery have the proper shields including PTO master shield and driveline shield.

Do not wear loose fitting clothing and keep long hair tied back and secured under a hat when working around equipment.

Learning Objectives for the Demonstration

To learn about the hazards of the turning parts on the PTO.

Describe the basic structure and components of a PTO

Describe the types of shields and guards available for the PTO

Understand prevention steps to take to reduce the risk of a PTO-related injury.

Materials Needed

Full size tractor with a PTO implement (not a rotary mower or other implement that might be dangerous to bystanders)

Tyvek coveralls stuffed with newspaper or straw

Several pieces of twine (varied lengths)

Demonstration Steps and Key Discussion Points

Make sure you practice this demonstration prior to doing it for a group.

Rope off a viewing area.

Attach and stage the tractor and implement in an actual work scenario.

Remove one end of the PTO shield and tie strong twine to the exposed U-joint and to arm or leg of the stuffed Tyvek suite (Figure 1). Key discussion points: Discuss the problems on PTO entanglement with the audience, explain the demonstration, and relate it to real-life situation.

From the operator's seat, safely start the tractor and engage the PTO. The Tyvek suit should wrap around the PTO shaft (Figure 2).

Shut off the tractor, disengage the PTO and secure the implement if necessary. Key discussion points: Discuss the demonstration including PTO speed, shielding, appropriate work clothing, and prevention.

Demonstration Images

Figure 1. Tyvek suite tied to the PTO.

Figure 2. Tyvek suit being pulled into the PTO.

Take-Home Points for the Demonstration

Understand the function and parts of the PTO.

Understand the hazards related to PTO entanglements.

Understand prevention strategies

Evaluation

We have provided a one page evaluation which has been designed to be used with participants after each lesson. The answer key is offered below.

Evaluation Questions Answer Key

Wear snug fitting clothing with no dangling strings or shoelaces

Entanglements usually occur when repairs or adjustments are being made to machine and PTO is left engaged.

A rotating drive shaft that transfers tractor engine power to implements.

(student response)

(student response)

For more information about PTO safety and recommendations, visit the resources below.